Why do humans dominate the planet?  Not, as often assumed, because of individual intelligence according to science writer, Matt Ridley.  Not because we have big brains.  Having smarter, cleverer people is not what makes societies work better.  He proposes that

“Human achievement is entirely a networking phenomenon.  It is by putting brains together through the division of labor — through trade and specialization — that human society stumbled upon a way to raise the living standards, carrying capacity, technological virtuosity and knowledge base of the species. …Human achievement is based on collective intelligence–the nodes in the human neural network are people themselves.  By each doing one thing and getting good at it, then sharing and combining the results through exchange, people become capable of doing things they do not even understand.”